Police in the northern province of Thai Nguyen are investigating a local man accused of attacking a journalist who was secretly filming activities inside a tea farm on Sunday.

Nguyen Duy Tung, 26, turned himself in right after he stabbed Trinh Luu Tuan in his arm. The reporter, 37, is in stable condition.

Tuan and his colleague Phung Van Dinh, both investigative journalists of national broadcaster Vietnam Television (VTV), were sent to the province to report undercover on the tea industry focusing on several farms, a VTV representative said Tuesday.

The two journalists pretended to be tea buyers and visited a farm owned by Tung’s father on Sunday afternoon.

Tuan secretly filmed how tea leaves were processed with a small camera hidden inside a pack of cigarettes.

Tung caught him and demanded he hand over the camera.

After Tuan refused to do so, Tung attacked the reporter and stabbed him.

The two journalists fled the scene, leaving the camera behind.

Tung told police he broke the camera when the men left, adding that he did not know they are reporters.

He said he thought the two men were his family's business rivals.

Authorities said they will look into the case and determine if either the journalists or the tea farm broke any law.